Silicon-Based Cooling Package with Diamond Coating for Heat-Generating Devices

ABSTRACT

Various embodiments of a thermal energy transfer apparatus that removes thermal energy from a heat-generating device are described. In one aspect, a thermal energy transfer apparatus comprises a silicon-based manifold having an internal cavity, a first primary side, and a second primary side opposite the first primary side. The second primary side of the manifold has at least one coolant inlet port and at least one coolant outlet port that are connected to the internal cavity of the manifold, the at least one coolant inlet port being at a position directly opposite a position on the diamond layer where the heat-generating device is received. A diamond layer covers at least a portion of the first primary side of the manifold such that the heat-generating device is in direct contact with the diamond layer when the heat-generating device is received on the first primary side of the manifold.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of U.S. Provisional PatentApplication No. 61/445,171, filed on Feb. 22, 2011, the entirety ofwhich is hereby incorporated by reference and made a part of thisspecification.

BACKGROUND

1. Technical Field

The present disclosure generally relates to the field of transfer ofthermal energy and, more particularly, to removal of thermal energy froma heat-generating device.

2. Description of the Related Art

Heat-generating devices, such as vertical-cavity surface-emitting lasers(VCSELs), light-emitting diodes (LEDs), laser diodes, microprocessorsand the like, generate thermal energy or heat when in operation.Regardless of which type of heat-generating device the case may be, heatgenerated by such a heat-generating device must be removed or dissipatedfrom the heat-generating device in order to achieve optimum performanceof the heat-generating device and keep the heat-generating device withinits safe operating temperature. With the form factor of heat-generatingdevices and the applications they are implemented in becoming ever morecompact, it is imperative to effectively dissipate the high-density heatgenerated in a small footprint area to ensure safe and optimum operationof heat-generating devices operating under such conditions.

Many metal-based water-cooled and air-cooled cooling packages have beendeveloped for use in compact packages to dissipate heat generated by thevarious types of heat-generating devices mentioned above. For instance,heat exchangers and heat pipes made of a metallic material with highthermal conductivity, such as copper, silver, aluminum or iron, arecommercially available. However, most metal-based heat exchangers andheat pipes experience oxidation, corrosion and/or crystallization afterlong periods of operation. Such fouling factors significantly reduce theheat transfer efficiency of metal-based heat exchangers and heat pipes.Other problems associated with the use of metal-based cooling packagesinclude, for example, issues with overall compactness of the package,corrosion of the metallic material in water-cooled applications,difficulty in manufacturing, etc. Yet, increasing demand for higherpower density in small form factor motivates the production of a compactcooling package with fewer or none of the aforementioned issues.

Heat-generating devices, such as vertical-cavity surface-emitting lasers(VCSELs), light-emitting diodes (LEDs), laser diodes, microprocessorsand the like, generate thermal energy or heat when in operation.Regardless of which type of heat-generating device the case may be, heatgenerated by such a heat-generating device must be removed or dissipatedfrom the heat-generating device in order to achieve optimum performanceof the heat-generating device and keep the heat-generating device withinits safe operating temperature. With the form factor of heat-generatingdevices and the applications they are implemented in becoming ever morecompact, it is imperative to effectively dissipate the high-density heatgenerated in a small footprint area to ensure safe and optimum operationof heat-generating devices operating under such conditions.

Many metal-based water-cooled and air-cooled cooling packages have beendeveloped for use in compact packages to dissipate heat generated by thevarious types of heat-generating devices mentioned above. For instance,heat exchangers and heat pipes made of a metallic material with highthermal conductivity, such as copper, silver, aluminum or iron, arecommercially available. However, most metal-based heat exchangers andheat pipes experience oxidation, corrosion and/or crystallization afterlong periods of operation. Such fouling factors significantly reduce theheat transfer efficiency of metal-based heat exchangers and heat pipes.Other problems associated with the use of metal-based cooling packagesinclude, for example, issues with overall compactness of the package,corrosion of the metallic material in water-cooled applications,difficulty in manufacturing, etc. Yet, increasing demand for higherpower density in small form factor motivates the production of a compactcooling package with fewer or none of the aforementioned issues.

SUMMARY

Various embodiments of the present disclosure pertain to a silicon-basedthermal energy transfer apparatus, or a cooling package, that removethermal energy from a heat-generating device. The novel and non-obvioussilicon-based thermal energy transfer apparatus eliminates problems withoxidation, corrosion and/or crystallization after long periods ofoperation as experienced by metal-based cooling packages. Other problemsassociated with the use of metal-based cooling packages such as issueswith overall compactness of the package, corrosion of the metallicmaterial in water-cooled applications, and difficulty in manufacturingmay also be eliminated or minimized.

With a thermal conductivity of at least 900 W/(m·K), diamond serves as amuch better thermal conductor than most commercially available metal andmetal alloys. With a layer of diamond coating on the surface of thesilicon-based thermal energy transfer apparatus, such that theheat-generating device is in direct contact with the layer of diamondwhen bonded, mounted, attached or otherwise fastened to the layer ofdiamond of the silicon-based thermal energy transfer apparatus, heatfrom the heat-generating device can quickly and widely spread across thelayer of diamond to allow much higher efficiency in heat dissipationthan existing technologies.

In one aspect, a thermal energy transfer apparatus that removes thermalenergy from a heat-generating device may comprise: a silicon-basedmanifold having an internal cavity, a first primary side, and a secondprimary side opposite the first primary side. The second primary sidemay have at least one coolant inlet port and at least one coolant outletport that are connected to the internal cavity of the manifold. The atleast one coolant inlet port may be at a position directly opposite aposition on the diamond layer where the heat-generating device isreceived. The apparatus further comprises a diamond layer covering atleast a portion of the first primary side of the manifold such that theheat-generating device is in direct contact with the diamond layer whenthe heat-generating device is received on the first primary side of themanifold.

In one embodiment, the silicon-based manifold may comprise asilicon-based first plate and a silicon-based second plate. The firstplate may have a first primary side and a second primary side oppositethe first primary side. The first primary side of the first plate may bethe first primary side of the manifold, the second primary side of thefirst plate may have a recess. The first plate may have an openingconnecting the first primary side and the recess on the second primaryside of the first plate such that a coolant flowing in the internalcavity of the manifold directly contacts the diamond layer. The secondplate may have a first primary side as the second primary side of themanifold and a second primary side opposite the first primary side. Thefirst primary side may have the at least one coolant inlet port and theat least one coolant outlet port. The second primary side may have arecess such that the opening in the first plate and the recess on thesecond primary side of the second plate form the internal cavity of themanifold when the first plate and the second plate are mated togetherwith the second primary side of the first plate facing the secondprimary side of the second plate. At least the first primary side of thesilicon-based first plate may have a surface roughness of a root meansquared (RMS) value of 2 microns or less.

In another embodiment, the silicon-based manifold may comprise asilicon-based first plate and a silicon-based second plate. The firstplate may have a first primary side and a second primary side oppositethe first primary side. The first primary side of the first plate may bethe first primary side of the manifold on which the diamond layer isdeposited. The second primary side of the first plate may have a recess.The second plate may have a first primary side as the second primaryside of the manifold and a second primary side opposite the firstprimary side. The first primary side of the second plate may have the atleast one coolant inlet port and the at least one coolant outlet port.The second primary side of the second plate may have a recess such thatthe recess on the second primary side of the first plate and the recesson the second primary side of the second plate form the internal cavityof the manifold when the first plate and the second plate are matedtogether with the second primary side of the first plate facing thesecond primary side of the second plate. At least the first primary sideof the silicon-based first plate has a surface roughness of an RMS valueof 2 microns or less.

In one embodiment, the diamond layer may have a thickness in a rangebetween 10 μm and 500 μm.

In one embodiment, the diamond layer may cover a substantial portion ofthe first primary side of the manifold.

In another aspect, a thermal energy transfer apparatus that removesthermal energy from a heat-generating device may comprise: asilicon-based base plate, a silicon-based first fin structure and asilicon-based second fin structure. The silicon-based base plate mayhave a first primary side, a second primary side opposite the firstprimary side, a first groove on the first primary side, and a secondgroove on the first primary side parallel to the first groove. Each ofthe first and second fin structures respectively may have a firstprimary side and a second primary side opposite the first primary side.Each of the first and second fin structures respectively may furtherhave, between the first primary side and the second primary side, a topedge, a bottom edge opposite the top edge, a front edge, and a back edgeopposite the front edge.

The first primary side, the top edge, the second primary side, and thebottom edge of the first fin structure may have a contiguous layer ofdiamond thereon. The first primary side, the top edge, the secondprimary side, and the bottom edge of the second fin structure may have acontiguous layer of diamond thereon. The bottom edge of the first finstructure may be received in the first groove, and the bottom edge ofthe second fin structure may be received in the second groove. The firstgroove and the second groove may be distanced from each other such thatwhen the heat-generating device is received between the first finstructure and the second fin structure the heat-generating device is indirect contact with the layer of diamond on the first fin structure andwith the layer of diamond on the second fin structure.

In one embodiment, the bottom edge of at least one of the first finstructure and the second fin structure may be V-shaped. At least one ofthe first groove and the second groove may be a V-shaped groove.

In one embodiment, at least one of the first and second fin structuresmay comprise at least one coolant inlet port on one of the respectiveedges, at least one coolant outlet port on one of the respective edges,and a coolant flow channel therein that connects the at least onecoolant inlet port and the at least one coolant outlet port to allow acoolant to flow through the respective fin structure.

In one embodiment, the at least one of the first and second finstructures may comprise a silicon-based first half-fin structure and asilicon-based second half-fin structure that are configured in a fashiondescribed below.

The first half-fin structure may have a first primary side as the firstprimary side of the respective fin structure, a second primary sideopposite the first primary side, a top edge as half of the top edge ofthe respective fin structure, a bottom edge as half of the bottom edgeof the respective fin structure, a front edge as half of the front edgeof the respective fin structure, and a back edge as half of the backedge of the respective fin structure. The second primary side of thefirst half-fin structure may have a recess. The first primary side ofthe first half-fin structure may have an opening connecting the firstprimary side of the first half-fin structure and the recess on thesecond primary side of the first half-fin structure such that thecoolant flowing in the coolant flow channel of the respective finstructure is in direct contact with the layer of diamond.

The second half-fin structure may have a first primary side as thesecond primary side of the respective fin structure, a second primaryside opposite the first primary side, a top edge as half of the top edgeof the respective fin structure, a bottom edge as half of the bottomedge of the respective fin structure, a front edge as half of the frontedge of the respective fin structure, and a back edge as half of theback edge of the respective fin structure. The second primary side ofthe second half-fin structure may have a recess. The first primary sideof the second half-fin structure may have an opening connecting thefirst primary side of the second half-fin structure and the recess onthe second primary side of the second half-fin structure such that thecoolant flowing in the coolant flow channel of the respective finstructure is in direct contact with the layer of diamond.

In one embodiment, at least the first primary side of the silicon-basedfirst half-fin structure may have a surface roughness of an RMS value of2 microns or less.

In another embodiment, at least one of the first and second finstructures may comprise a silicon-based first half-fin structure and asilicon-based second half-fin structure that are configured in a fashiondescribed below.

The first half-fin structure may have a first primary side as the firstprimary side of the respective fin structure, a second primary sideopposite the first primary side, a top edge as half of the top edge ofthe respective fin structure, a bottom edge as half of the bottom edgeof the respective fin structure, a front edge as half of the front edgeof the respective fin structure, and a back edge as half of the backedge of the respective fin structure. The second primary side of thefirst half-fin structure may have a recess.

The second half-fin structure may have a first primary side as the firstprimary side of the respective fin structure, a second primary sideopposite the first primary side, a top edge as half of the top edge ofthe respective fin structure, a bottom edge as half of the bottom edgeof the respective fin structure, a front edge as half of the front edgeof the respective fin structure, and a back edge as half of the backedge of the respective fin structure. The second primary side of thesecond half-fin structure may have a recess such that the coolant flowchannel of the respective fin structure is formed when the firsthalf-fin structure and the second half-fin structure are mated togetherwith the second primary side of the first half-fin structure facing thesecond primary side of the second half-fin structure.

In one embodiment, at least the first primary side of the silicon-basedfirst half-fin structure has a surface roughness of an RMS value of 2microns or less.

In one embodiment, the layer of diamond on at least one of the first finstructure and the second fin structure may have a thickness in a rangebetween 10 μm and 500 μm.

In one aspect, a method may comprise: polishing a first primary side ofa silicon wafer; forming a layer of diamond on the first primary side ofthe silicon wafer; micromachining a second primary side of the siliconwafer that is opposite the first primary side to form at least onerecess on the second primary side; cutting the silicon wafer to providea first half-structure such that a first primary side of the firsthalf-structures is covered by a respective layer of diamond and a secondprimary side of the first half-structure has a respective one of the atleast one recess; and bonding a silicon-based second half-structure withthe first half-fin structure to form a silicon-based manifold, thesecond half-structure having at least one coolant inlet port and atleast one coolant outlet port through which a coolant flows in and outof the manifold, respectively.

In one embodiment, polishing the first primary side of the silicon wafermay comprise polishing the first primary side of the silicon wafer suchthat the first primary side of the silicon wafer has a surface roughnessof an RMS value of 2 microns or less.

In one embodiment, forming the layer of diamond on the first primaryside of the silicon wafer may comprise forming, on the first primaryside of the silicon wafer, a layer of diamond having a thickness in arange between 10 μm and 500 μm.

In one embodiment, micromachining the second primary side of the siliconwafer to form at least one recess on the second primary side maycomprise micromachining the second primary side of the silicon wafer toform at least one recess on the second primary side such that at least aportion of the layer of diamond is exposed on the second primary side ofthe wafer. Furthermore, cutting the silicon wafer to provide the firsthalf-structure such that a first primary side of the firsthalf-structures is covered by a respective layer of diamond and a secondprimary side of the first half-structure has a respective one of the atleast one recess may comprise cutting the silicon wafer to provide thefirst half-structure such that the first primary side of the firsthalf-structures is covered by the respective layer of diamond and thesecond primary side of the first half-structure has a respective one ofthe at least one recess that exposes the respective layer of diamond onthe second primary side of the first half-structure.

In one embodiment, the method may further comprise: attaching aheat-generating device to the manifold such that the heat-generatingdevice is in direct contact with the layer of diamond on the firstprimary side of the first half-structure; and flowing the coolant intothe manifold through the coolant inlet port and out of the manifoldthrough the coolant outlet port to remove a portion of heat from theheat-generating device.

BRIEF DESCRIPTION OF THE DRAWINGS

In the detailed description that follows, embodiments are described asillustrations since various changes and modifications will becomeapparent to those skilled in the art from the following detaileddescription. The use of the same reference numbers in differentindicates similar or identical items. It is appreciable that the figuresare not necessarily in scale as some components may be shown as out ofproportion than the size in actual implementation in order to clearlyillustrate the concept of the present disclosure.

FIG. 1 is a three-dimensional view of a thermal energy transferapparatus that removes thermal energy from a heat-generating device inaccordance with one embodiment of the present disclosure.

FIG. 2 is another three-dimensional view of the thermal energy transferapparatus of FIG. 1 in accordance with one embodiment of the presentdisclosure.

FIG. 3 is a cross-sectional view of the thermal energy transferapparatus of FIG. 1 in accordance with one embodiment of the presentdisclosure.

FIG. 4 is a cross-sectional view of the thermal energy transferapparatus of FIG. 1 in accordance with another embodiment of the presentdisclosure.

FIG. 5 is a three-dimensional view of a fin structure of a thermalenergy transfer apparatus that removes thermal energy from aheat-generating device in accordance with one embodiment of the presentdisclosure.

FIG. 6A is a cross-sectional view of line BB of the fin structure ofFIG. 5 in accordance with one embodiment of the present disclosure.

FIG. 6B is a side view of line CC of the fin structure of FIG. 6A inaccordance with one embodiment of the present disclosure.

FIG. 7A is a cross-sectional view of line BB of the fin structure ofFIG. 5 in accordance with another embodiment of the present disclosure.

FIG. 7B is a side view of line CC of the fin structure of FIG. 7A inaccordance with one embodiment of the present disclosure.

FIG. 8 is a three-dimensional view of a fin structure of a thermalenergy transfer apparatus that removes thermal energy from aheat-generating device in accordance with another embodiment of thepresent disclosure.

FIG. 9A is a cross-sectional view of line DD of the fin structure ofFIG. 8 in accordance with one embodiment of the present disclosure.

FIG. 9B is a side view of line EE of the fin structure of FIG. 9A inaccordance with one embodiment of the present disclosure.

FIG. 10 is a side view of a thermal energy transfer apparatus thatremoves thermal energy from a heat-generating device in accordance withanother embodiment of the present disclosure.

FIG. 11 is a three-dimensional view of the thermal energy transferapparatus of FIG. 10 in accordance with one embodiment of the presentdisclosure.

FIG. 12 is a flowchart of a process of fabricating a thermal energytransfer apparatus that removes thermal energy from a heat-generatingdevice in accordance with one embodiment of the present disclosure.

DETAILED DESCRIPTION Overview

The present disclosure describes embodiments of a thermal energytransfer apparatus that removes thermal energy from a light-emittingdevice. While aspects of described techniques relating to a thermalenergy transfer apparatus that removes thermal energy from alight-emitting device can be implemented in any number of differentapplications, the disclosed embodiments are described in context of thefollowing exemplary configurations.

Illustrative First Thermal Energy Transfer Apparatus

FIG. 1 illustrates a three-dimensional view of a thermal energy transferapparatus 100 that removes thermal energy from a heat-generating device101 when the heat-generating device 101 is bonded, mounted, attached orotherwise fastened to the thermal energy transfer apparatus 100. Theheat-generating device 101 may be, for example, a VCSEL or amicroprocessor chip.

The thermal energy transfer apparatus 100 comprises a silicon-basedmanifold 110. The manifold 110 has an internal cavity 108 (not visiblein FIG. 1 but partially visible in FIG. 2), a first primary side (i.e.,the top surface of the manifold 110 which faces the heat-generatingdevice 101 in FIG. 1), and a second primary side opposite the firstprimary side (i.e., the bottom surface of the manifold 110 which is notvisible in FIG. 1). In one embodiment, the silicon-based manifold 110comprises a silicon-based first plate 103 and a silicon-based secondplate 104. Detailed description of the silicon-based first plate 103 andthe silicon-based second plate 104 will be provided below with referenceto FIGS. 3 and 4.

The thermal energy transfer apparatus 100 further comprises a diamondlayer 102. The diamond layer 102 covers at least a portion of the firstprimary side of the manifold 110 such that the heat-generating device101 is in direct contact with the diamond layer 102 when theheat-generating device 101 is received on the first primary side of themanifold 110. For example, as shown in FIG. 1, the diamond layer 102 maycover substantially the entire first primary side of the manifold 110.When the heat-generating device 101 is bonded, mounted, attached orotherwise fastened to the diamond layer 102 of the thermal energytransfer apparatus 100, heat from the heat-generating device 102 canquickly and widely spread across the layer of diamond since diamond hasexcellent thermal conductivity, i.e., 900-2,320 W/(m·K). As such, heatfrom the heat-generating device 102 can be better dissipated by themanifold 110 in addition to being radiated and convected to theambience. This technique results in much higher efficiency in heatdissipation than existing cooling package technologies.

FIG. 2 illustrates another three-dimensional view of the thermal energytransfer apparatus 100 of FIG. 1 in accordance with one embodiment ofthe present disclosure.

The second primary side of the manifold 110 may have at least onecoolant inlet port and at least one coolant outlet port that areconnected to the internal cavity 108 of the manifold 110. The number andlocation of each of the at least one coolant inlet port and the at leastone coolant outlet port are designed so as to enhance heat transfer to acoolant flowing through the manifold 110. In one embodiment, as shown inFIG. 2, the second primary side of the manifold 110 has one coolantinlet port 105 and four coolant output ports 106A, 106B, 106C and 106D.To optimize the heat transfer efficiency, the at least one coolant inletport, e.g., the coolant inlet port 105, is at a position directlyopposite a position on the diamond layer 102 where the heat-generatingdevice 101 is received. Detailed description about the location of thecoolant inlet port 105 will be provided below with reference to FIGS. 3and 4.

In other embodiments, there may be more coolant inlet port than shown inFIG. 2. Even with more than one coolant inlet port, the at least onecoolant inlet port may be designed to be positioned directly opposite aposition on the diamond layer 102 where the heat-generating device 101is bonded, mounted, attached or otherwise fastened to the diamond layer102.

The coolant output ports 106A, 106B, 106C and 106D surround the coolantinlet port 105 so that the coolant flowing into the manifold 110 has tospread out in four directions, thus absorbing the heat spread by thediamond layer 102 along the way, in order to flow out of the manifold110 from the coolant output ports 106A, 106B, 106C and 106D. In otherembodiments, there may be fewer or more coolant output ports than shownin FIG. 2, and those coolant output ports may be at different positionson the second primary side of the manifold 110.

FIG. 3 illustrates a cross-sectional view of the thermal energy transferapparatus 100 of FIG. 1 in accordance with one embodiment of the presentdisclosure.

In one embodiment, as shown in FIG. 3, the first plate 103 has a firstprimary side, i.e., the top side shown in FIG. 3, and a second primaryside opposite the first primary side, i.e., the bottom side shown inFIG. 3. The first primary side of the first plate 103 is the firstprimary side of the manifold 110 on which the diamond layer 102 isdeposited. The second primary side of the first plate 103 has a recess.

The second plate 104 has a first primary side, i.e., the bottom sideshown in FIG. 3, as the second primary side of the manifold 110 and asecond primary side opposite the first primary side, i.e., the top sideshown in FIG. 3. The first primary side of the second plate 104 has theat least one coolant inlet port, e.g., the coolant inlet port 105, andthe at least one coolant outlet port, e.g., the coolant outlet ports106A, 106B, 106C and 106D. The second primary side of the second plate104 has a recess.

As shown in FIG. 3, the coolant inlet port 105 is directly below theheat-generating device 101. This allows a coolant 107 flowing into themanifold 110 through the coolant inlet port 105 to impinge on the secondprimary side of the first plate 103 which is directly below theheat-generating device 101. This has been shown experimentally to resultin optimal heat transfer from the heat-generating device 101 to thecoolant 107. Furthermore, with at least a portion of the heat from theheat-generating device 101 spread across the diamond layer 102, thisamount of heat can be more uniformly transferred from the diamond layer102 to the first plate 103, and subsequently to the coolant 107 as thecoolant 107 flows through the manifold 110 before exiting the coolantoutlet ports 106A, 106B, 106C and 106D.

The recess on the second primary side of the first plate 103 and therecess on the second primary side of the second plate 104 form theinternal cavity 108 of the manifold 110 when the first plate 103 and thesecond plate 104 are mated together with the second primary side of thefirst plate 103 facing the second primary side of the second plate 104.

In one embodiment, the first plate 103 and the second plate 104 are eachmicromachined from a single-crystal silicon wafer. In anotherembodiment, the first plate 103 and the second plate 104 are eachmicromachined from a poly-crystal silicon wafer. The first plate 103 andthe second plate 104 may be made from the same wafer or differentwafers.

In one embodiment, at least the first primary side of the first plate103 is polished to have a surface roughness of a root mean squared (RMS)value of 2 microns or less. In another embodiment, both the firstprimary side and the second primary side of the first plate 103 arepolished to have a surface roughness of an RMS value of 2 microns orless.

As the diamond layer 102 is deposited or otherwise formed on the firstprimary side of the first plate 103, a highly polished surface on thefirst primary side of the first plate 103, i.e., having a low surfaceroughness RMS value, helps the formation of the diamond layer 102 havingmirror-polished surfaces.

Having a highly polished surface on the second primary side of the firstplate 103 supports a laminar flow of the coolant 107 in the internalcavity 108 of the manifold 110. Laminar flow of the coolant 107 resultsin better heat transfer by convection compared to the case of turbulentflow. If the coolant 107 has a turbulent flow, e.g., at least partly dueto the second primary side of the first plate 103 having rough surfacefinish, not only convective heat transfer is less than desirable with aturbulent flow but air pockets may likely form between the coolant 107and the second primary side of the first plate 103 and further degradeheat transfer to the coolant 107.

In one embodiment, the diamond layer 102 covers a substantial portion ofthe first primary side of the manifold. For example, as shown in FIGS. 1and 3, the diamond layer 102 covers substantially the entire firstprimary side of the manifold 110, which is the first primary side of thefirst plate 103. In other embodiments, the diamond layer 102 covers onlya portion of the first primary side of the first plate 103 such that theheat-generating device 101 directly contacts the diamond layer 102, notthe first primary side of the first plate 103. In other words, thedimensions W1 and W2 of the diamond layer 102, as shown in FIG. 3, maybe different in different embodiments.

In one embodiment, the diamond layer 102 has a thickness, shown as thedimension D2 in FIG. 3, in a range between 10 μm and 500 μm. Thedimension D2 may be the same as or different from the thickness of thefirst plate 103, shown as the dimension D1 in FIG. 3.

FIG. 4 illustrates a cross-sectional view of the thermal energy transferapparatus 100 of FIG. 1 in accordance with another embodiment of thepresent disclosure.

The embodiment of the thermal energy transfer apparatus 100 shown inFIG. 4 and the embodiment of the thermal energy transfer apparatus 100shown in FIG. 3 are similar. In the interest of brevity, features of theembodiment of the thermal energy transfer apparatus 100 shown in FIG. 4that are similar to those of the embodiment of the thermal energytransfer apparatus 100 shown in FIG. 3 will not be repeated herein.

The main difference between the embodiment of the thermal energytransfer apparatus 100 shown in FIG. 4 and the embodiment of the thermalenergy transfer apparatus 100 shown in FIG. 3 is that the first plate103 has an opening connecting the first primary side and the recess onthe second primary side of the first plate 103. This way, the diamondlayer 102 is exposed to the coolant 107 and, accordingly, the coolant107 flowing in the internal cavity 108 of the manifold 110 directlycontacts the diamond layer 102 to transfer heat away from the diamondlayer 102. Given that heat in the diamond layer 102 can be directlytransferred to the coolant 107 without having to traverse through thethickness of the first plate 103, as in the case shown in FIG. 3, it isbelieved the embodiment of the thermal energy transfer apparatus 100shown in FIG. 4 can better transfer heat away from the heat-generatingdevice 101 than the embodiment shown in FIG. 3.

In one embodiment, the first plate 103 and the second plate 104 are eachmicromachined from a single-crystal silicon wafer. In anotherembodiment, the first plate 103 and the second plate 104 are eachmicromachined from a poly-crystal silicon wafer. The first plate 103 andthe second plate 104 may be fabricated from the same wafer or differentwafers. After the formation of the diamond layer 102 on the firstprimary side of the first plate 103, the second primary side of thefirst plate 103 is etched to create an opening in the first plate 103 toexpose the diamond layer 102 on the second primary side of the firstplate 103.

In one embodiment, at least the first primary side of the first plate103 is polished to have a surface roughness of a root mean squared (RMS)value of 2 microns or less. As the diamond layer 102 is deposited orotherwise formed on the first primary side of the first plate 103, ahighly polished surface on the first primary side of the first plate103, i.e., having a low surface roughness RMS value, helps the formationof the diamond layer 102 having mirror-polished surfaces. Having ahighly polished surface on the diamond layer 102 supports a laminar flowof the coolant 107 in the internal cavity 108 of the manifold 110.

In one embodiment, the diamond layer 102 covers a substantial portion ofthe first primary side of the manifold. For example, as shown in FIGS. 1and 4, the diamond layer 102 covers substantially the entire firstprimary side of the manifold 110, which is the first primary side of thefirst plate 103. In other embodiments, the diamond layer 102 covers onlya portion of the first primary side of the first plate 103 such that theheat-generating device 101 directly contacts the diamond layer 102, notthe first primary side of the first plate 103. In other words, thedimensions W3 and W4 of the diamond layer 102, as shown in FIG. 4, maybe different in different embodiments.

In one embodiment, the diamond layer 102 has a thickness, shown as thedimension D3 in FIG. 4, in a range between 10 μm and 500 μm.

Illustrative Second Thermal Energy Transfer Apparatus

FIG. 5 illustrates a three-dimensional view of a fin structure 200 of athermal energy transfer apparatus that removes thermal energy from aheat-generating device in accordance with one embodiment of the presentdisclosure.

The fin structure 200 has a first primary side and a second primary sideopposite the first primary side. Between the first primary side and thesecond primary side, the fin structure 200 has a top edge, a bottom edgeopposite the top edge, a front edge, and a back edge opposite the frontedge.

As shown in FIG. 5, the fin structure 200 comprises a silicon-basedfirst half-fin structure 208 and a silicon-based second half-finstructure 209. Detailed description of the silicon-based first half-finstructure 208 and the silicon-based second half-fin structure 209 willbe provided below with reference to FIGS. 6A, 6B, 7A and 7B.

The first primary side, the top edge, the second primary side, and thebottom edge of the first fin structure 200 have a contiguous layer ofdiamond 210 coated thereon. That is, at least a portion of each of thefirst primary side, the top edge, the second primary side, and thebottom edge of the first fin structure 200 is covered by a portion ofthe layer of diamond 210. In one embodiment, substantially the entirefirst primary side, the top edge, the second primary side, and thebottom edge of the first fin structure 200 are covered by the layer ofdiamond 210.

In one embodiment, the bottom edge of the fin structure 200 and isV-shaped. In other embodiments, the bottom edge and at least one otheredge of the fin structure 200 are V-shaped. For example, the top edge,bottom edge, front edge and back edge of the fin structure 200 may beV-shaped.

FIG. 6A illustrates a cross-sectional view of the fin structure 200 ofFIG. 5 in accordance with one embodiment of the present disclosure. FIG.6B illustrates a side view of the fin structure 200 of FIG. 6A inaccordance with one embodiment of the present disclosure.

In one embodiment, the fin structure 200 comprises at least one coolantinlet port on one of the respective edges, at least one coolant outletport on one of the respective edges, and a coolant flow channel thereinthat connects the at least one coolant inlet port and the at least onecoolant outlet port to allow a coolant to flow through the fin structure200.

The first half-fin structure 208 has a first primary side, i.e., the topside shown in FIG. 6A, as the first primary side of the fin structure200, and a second primary side opposite the first primary side, i.e.,the bottom side shown in FIG. 6A. Between the first primary side and thesecond primary side, the first half-fin structure 208 has a top edge ashalf of the top edge of the fin structure 200, a bottom edge as half ofthe bottom edge of the fin structure 200, a front edge as half of thefront edge of the fin structure 200, and a back edge as half of the backedge of the fin structure 200. The second primary side of the firsthalf-fin structure 208 has a recess 201 that forms half of the coolantinlet port, the coolant flow channel, and the coolant outlet port.

The second half-fin structure 209 has a first primary side, i.e., thebottom side shown in FIG. 6A, as the second primary side of the finstructure 200, and a second primary side opposite the first primaryside. Between the first primary side and the second primary side, thesecond half-fin structure 209 has a top edge as the other half of thetop edge of the fin structure 200, a bottom edge as the other half ofthe bottom edge of the fin structure 200, a front edge as the other halfof the front edge of the fin structure 200, and a back edge as the otherhalf of the back edge of the fin structure 200. The second primary sideof the second half-fin structure 209 has a recess 202 that forms theother half of the coolant inlet port, the coolant flow channel, and thecoolant outlet port.

The coolant flow channel of the fin structure 200 is formed when thefirst half-fin structure 208 and the second half-fin structure 209 aremated together with the second primary side of the first half-finstructure facing the second primary side of the second half-finstructure.

In one embodiment, the first half-fin structure 208 and the secondhalf-fin structure 209 are each micromachined from a single-crystalsilicon wafer. In another embodiment, the first half-fin structure 208and the second half-fin structure 209 are each micromachined from apoly-crystal silicon wafer. The first half-fin structure 208 and thesecond half-fin structure 209 may be made from the same wafer ordifferent wafers.

In one embodiment, at least the first primary side of the first half-finstructure 208 is polished to have a surface roughness of an RMS value of2 microns or less. In another embodiment, the first primary side and thesecond primary side of the first half-fin structure 208 are polished tohave a surface roughness of an RMS value of 2 microns or less.Alternatively or additionally, at least the first primary side of thesecond half-fin structure 209 is polished to have a surface roughness ofan RMS value of 2 microns or less. Alternatively or additionally, thefirst primary side and the second primary side of the second half-finstructure 209 are polished to have a surface roughness of an RMS valueof 2 microns or less. Benefits of having a highly polished surface havebeen described above and thus, in the interest of brevity, will not berepeated herein.

In one embodiment, the layer of diamond 210 on the first fin structure200 has a thickness T2 in a range between 10 μm and 500 μm. Thedimension T2 may be the same as or different from the thickness T1 ofthe first half-fin structure 208 and the second half-fin structure 209.

FIG. 7A illustrates a cross-sectional view of the fin structure 200 ofFIG. 5 in accordance with another embodiment of the present disclosure.FIG. 7B illustrates a side view of the fin structure 200 of FIG. 7A inaccordance with one embodiment of the present disclosure.

The embodiment of the fin structure 200 shown in FIGS. 7A, 7B and theembodiment of the fin structure 200 shown in FIGS. 6A, 6B are similar.In the interest of brevity, features of the embodiment of the finstructure 200 shown in FIGS. 7A, 7B that are similar to those of theembodiment of the sin structure 200 shown in FIGS. 6A, 6B will not berepeated herein.

The main difference between the embodiment of the fin structure 200shown in FIGS. 7A, 7B and the embodiment of the fin structure 200 shownin FIGS. 6A, 6B is that either or both of the first half-fin structure208 and the second half-fin structure 209 have an opening connecting itsfirst primary side and the recess on its second primary side. This way,the layer of diamond 210 is exposed to the coolant and, accordingly, thecoolant flowing in the coolant flow channel of the fin structure 200directly contacts the layer of diamond 210 to transfer heat away fromthe layer of diamond 210. Given that heat in the layer of diamond 102can be directly transferred to the coolant without having to traversethrough the thickness of the respective half-fin structure, it isbelieved the embodiment of the fin structure 200 shown in FIGS. 7A, 7Bcan better transfer heat away from a heat-generating device that isbonded, mounted, attached or otherwise fastened to the layer of diamond210 than the embodiment shown in FIGS. 6A, 6B.

In one embodiment, the first half-fin structure 208 and the secondhalf-fin structure 209 are each micromachined from a single-crystalsilicon wafer. In another embodiment, the first half-fin structure 208and the second half-fin structure 209 are each micromachined from apoly-crystal silicon wafer. The first half-fin structure 208 and thesecond half-fin structure 209 may be fabricated from the same wafer ordifferent wafers. After the formation of the layer of diamond 210 on thefirst primary side of the first half-fin structure 208, the secondprimary side of the first half-fin structure 208 is etched to create anopening in the first half-fin structure 208 to expose the layer ofdiamond 210 on the second primary side of the first half-fin structure208. A similar fabrication process may be carried out for the secondhalf-fin structure 209.

In one embodiment, at least the first primary side of the first half-finstructure 208 is polished to have a surface roughness of an RMS value of2 microns or less. In another embodiment, the first primary side and thesecond primary side of the first half-fin structure 208 are polished tohave a surface roughness of an RMS value of 2 microns or less.Alternatively or additionally, at least the first primary side of thesecond half-fin structure 209 is polished to have a surface roughness ofan RMS value of 2 microns or less. Alternatively or additionally, thefirst primary side and the second primary side of the second half-finstructure 209 are polished to have a surface roughness of an RMS valueof 2 microns or less. Benefits of having a highly polished surface havebeen described above and thus, in the interest of brevity, will not berepeated herein.

In one embodiment, the layer of diamond 210 has a thickness, shown asthe dimension T3 in FIGS. 7A, 7B, in a range between 10 μm and 500 μm.

FIG. 8 is a three-dimensional view of a fin structure 300 of a thermalenergy transfer apparatus that removes thermal energy from aheat-generating device in accordance with another embodiment of thepresent disclosure.

The fin structure 300 comprises a silicon-based fin structure 311. Thefin structure 311 has a first primary side and a second primary sideopposite the first primary side. Between the first primary side and thesecond primary side, the fin structure 311 has a top edge, a bottom edgeopposite the top edge, a front edge, and a back edge opposite the frontedge.

The first primary side, the top edge, the second primary side, and thebottom edge of the first fin structure 311 have a contiguous layer ofdiamond 312 coated thereon. That is, at least a portion of each of thefirst primary side, the top edge, the second primary side, and thebottom edge of the first fin structure 311 is covered by a portion ofthe layer of diamond 312. In one embodiment, substantially the entirefirst primary side, the top edge, the second primary side, and thebottom edge of the first fin structure 311 are covered by the layer ofdiamond 312.

In one embodiment, the bottom edge of the fin structure 311 and isV-shaped. In other embodiments, the bottom edge and at least one otheredge of the fin structure 311 are V-shaped. For example, the top edge,bottom edge, front edge and back edge of the fin structure 311 may beV-shaped.

In one embodiment, the fin structure 311 is micromachined from asingle-crystal silicon wafer. In another embodiment, the fin structure311 is micromachined from a poly-crystal silicon wafer.

In one embodiment, at least the first primary side of the fin structure311 is polished to have a surface roughness of an RMS value of 2 micronsor less. In another embodiment, the first primary side and the secondprimary side of the fin structure 311 are polished to have a surfaceroughness of an RMS value of 2 microns or less. Alternatively, the firstprimary side, the second primary side, the top edge and the bottom edgeof the fin structure 311 are polished to have a surface roughness of anRMS value of 2 microns or less. Benefits of having a highly polishedsurface have been described above and thus, in the interest of brevity,will not be repeated herein.

In one embodiment, the layer of diamond 312 on the fin structure 311 hasa thickness in a range between 10 μm and 500 μm.

FIG. 9A is a cross-sectional view of the fin structure 300 of FIG. 8 inaccordance with one embodiment of the present disclosure. FIG. 9B is aside view of the fin structure 300 of FIG. 9A in accordance with oneembodiment of the present disclosure.

FIG. 10 is a side view of a thermal energy transfer apparatus 400 thatremoves thermal energy from a heat-generating device in accordance withanother embodiment of the present disclosure. FIG. 11 is athree-dimensional view of the thermal energy transfer apparatus 400 ofFIG. 10 in accordance with one embodiment of the present disclosure.

The thermal energy transfer apparatus 400 removes thermal energy fromone or more heat-generating device 414. Although there are a fixednumber of heat-generating devices 414 shown in FIGS. 10 and 11, invarious embodiments the number of the heat-generating devices 414 may begreater or smaller than that shown in FIGS. 10 and 11.

The thermal energy transfer apparatus 400 comprises a silicon-based baseplate 413 and a plurality of silicon-based fin structures including asilicon-based first fin structure and a silicon-based second finstructure. In one embodiment, least one of the plurality ofsilicon-based fin structures of the apparatus 400 may be the finstructure 200 shown in FIGS. 5, 6A, 6B, 7A and 7B. In anotherembodiment, least one of the plurality of silicon-based fin structuresof the apparatus 400 may be the fin structure 300 shown in FIGS. 8, 9Aand 9B. For illustrative purpose only, the fin structure 300 is shown aseach of the plurality of fin structures of the apparatus 400 in FIGS. 10and 11.

The silicon-based base plate 413 has a first primary side, a secondprimary side opposite the first primary side, and a plurality ofparallel grooves. For example, a first groove on the first primary sideis parallel to a second groove on the first primary side of the baseplate 413.

The bottom edge of each of the plurality of fin structures is receivedin a respective one of the grooves. The groove are distanced from eachother such that when a respective heat-generating device 414 is receivedbetween two neighboring fin structures the heat-generating device 414 isin direct contact with the layer of diamond 312 on each of the two finstructures 300.

In one embodiment, the bottom edge of at least one of the fin structuresis V-shaped. At least one of the grooves is a V-shaped groove to receivethe V-shaped bottom edge of the fin structure.

Illustrative Fabrication Process

FIG. 12 illustrates a flowchart of a process 500 of fabricating athermal energy transfer apparatus that removes thermal energy from aheat-generating device in accordance with one embodiment of the presentdisclosure.

At 502, the process 500 polishes a first primary side of a siliconwafer. At 504, the process 500 forms a layer of diamond on the firstprimary side of the silicon wafer. At 506, the process 500 micromachinesa second primary side of the silicon wafer that is opposite the firstprimary side to form at least one recess on the second primary side. At508, the process 500 cuts the silicon wafer to provide a firsthalf-structure such that a first primary side of the firsthalf-structures is covered by a respective layer of diamond and a secondprimary side of the first half-structure has a respective one of the atleast one recess. At 510, the process 500 bonds a silicon-based secondhalf-structure with the first half-fin structure to form a silicon-basedmanifold, the second half-structure having at least one coolant inletport and at least one coolant outlet port through which a coolant flowsin and out of the manifold, respectively. Accordingly, the process 500may be utilized to fabricate the components of the manifold 110 and thecomponents of the fin structure 200 described above.

In one embodiment, the first primary side of the silicon wafer ispolished such that the first primary side of the silicon wafer has asurface roughness of an RMS value of 2 microns or less.

In one embodiment, on the first primary side of the silicon wafer, alayer of diamond is formed and has a thickness in a range between 10 μmand 500 μm.

In one embodiment, the second primary side of the silicon wafer ismicromachined to form at least one recess on the second primary sidesuch that at least a portion of the layer of diamond is exposed on thesecond primary side of the wafer. Furthermore, the silicon wafer is cutto provide the first half-structure such that the first primary side ofthe first half-structures is covered by the respective layer of diamondand the second primary side of the first half-structure has a respectiveone of the at least one recess that exposes the respective layer ofdiamond on the second primary side of the first half-structure.

In one embodiment, the process 500 further comprises: attaching aheat-generating device to the manifold such that the heat-generatingdevice is in direct contact with the layer of diamond on the firstprimary side of the first half-structure; and causing the coolant toflow into the manifold through the coolant inlet port and out of themanifold through the coolant outlet port to remove a portion of heatfrom the heat-generating device.

CONCLUSION

The above-described techniques pertain to silicon-based thermal energytransfer heat-generating devices. The novel and non-obvioussilicon-based thermal energy transfer apparatus eliminates problems withoxidation, corrosion and/or crystallization after long periods ofoperation as experienced by metal-based cooling packages. Other problemsassociated with the use of metal-based cooling packages such as issueswith overall compactness of the package, corrosion of the metallicmaterial in water-cooled applications, and difficulty in manufacturingmay also be eliminated or minimized.

Although the techniques have been described in language specific tostructural features and/or methodological acts, it is to be understoodthat the appended claims are not necessarily limited to the specificfeatures or acts described. Rather, the specific features and acts aredisclosed as exemplary forms of implementing such techniques.Furthermore, although the techniques have been illustrated in thecontext of cooling package for a VCSEL and a microprocessor chip, thetechniques may be applied in any other suitable context such as, forexample, cooling package for laser diodes and LEDs.

1. A thermal energy transfer apparatus that removes thermal energy froma heat-generating device, the apparatus comprising: a silicon-basedmanifold having an internal cavity, a first primary side, and a secondprimary side opposite the first primary side, the second primary sidehaving at least one coolant inlet port and at least one coolant outletport that are connected to the internal cavity of the manifold, the atleast one coolant inlet port being at a position directly opposite aposition on the diamond layer where the heat-generating device isreceived; and a diamond layer covering at least a portion of the firstprimary side of the manifold such that the heat-generating device is indirect contact with the diamond layer when the heat-generating device isreceived on the first primary side of the manifold.
 2. The apparatus ofclaim 1, wherein the silicon-based manifold comprises: a silicon-basedfirst plate, the first plate having a first primary side and a secondprimary side opposite the first primary side, the first primary side ofthe first plate being the first primary side of the manifold, the secondprimary side of the first plate having a recess, the first plate havingan opening connecting the first primary side and the recess on thesecond primary side of the first plate such that a coolant flowing inthe internal cavity of the manifold directly contacts the diamond layer;and a silicon-based second plate, the second plate having a firstprimary side as the second primary side of the manifold and a secondprimary side opposite the first primary side, the first primary sidehaving the at least one coolant inlet port and the at least one coolantoutlet port, the second primary side having a recess such that theopening in the first plate and the recess on the second primary side ofthe second plate form the internal cavity of the manifold when the firstplate and the second plate are mated together with the second primaryside of the first plate facing the second primary side of the secondplate.
 3. The apparatus of claim 2, wherein at least the first primaryside of the silicon-based first plate has a surface roughness of a rootmean squared (RMS) value of 2 microns or less.
 4. The apparatus of claim1, wherein the silicon-based manifold comprises: a silicon-based firstplate, the first plate having a first primary side and a second primaryside opposite the first primary side, the first primary side of thefirst plate being the first primary side of the manifold on which thediamond layer is deposited, the second primary side of the first platehaving a recess; and a silicon-based second plate, the second platehaving a first primary side as the second primary side of the manifoldand a second primary side opposite the first primary side, the firstprimary side of the second plate having the at least one coolant inletport and the at least one coolant outlet port, the second primary sideof the second plate having a recess such that the recess on the secondprimary side of the first plate and the recess on the second primaryside of the second plate form the internal cavity of the manifold whenthe first plate and the second plate are mated together with the secondprimary side of the first plate facing the second primary side of thesecond plate.
 5. The apparatus of claim 4, wherein at least the firstprimary side of the silicon-based first plate has a surface roughness ofa root mean squared (RMS) value of 2 microns or less.
 6. The apparatusof claim 1, wherein the diamond layer has a thickness in a range between10 μm and 500 μm.
 7. The apparatus of claim 1, wherein the diamond layercovers a substantial portion of the first primary side of the manifold.8. A thermal energy transfer apparatus that removes thermal energy froma heat-generating device, the apparatus comprising: a silicon-based baseplate having a first primary side, a second primary side opposite thefirst primary side, a first groove on the first primary side, and asecond groove on the first primary side parallel to the first groove;and a silicon-based first fin structure and a silicon-based second finstructure, each of the first and second fin structures respectivelyhaving a first primary side and a second primary side opposite the firstprimary side, each of the first and second fin structures respectivelyfurther having, between the first primary side and the second primaryside, a top edge, a bottom edge opposite the top edge, a front edge, anda back edge opposite the front edge, the first primary side, the topedge, the second primary side, and the bottom edge of the first finstructure having a contiguous layer of diamond thereon, the firstprimary side, the top edge, the second primary side, and the bottom edgeof the second fin structure having a contiguous layer of diamondthereon, the bottom edge of the first fin structure being received inthe first groove, the bottom edge of the second fin structure beingreceived in the second groove, the first groove and the second groovebeing distanced from each other such that when the heat-generatingdevice is received between the first fin structure and the second finstructure the heat-generating device is in direct contact with the layerof diamond on the first fin structure and with the layer of diamond onthe second fin structure.
 9. The apparatus of claim 8, wherein thebottom edge of at least one of the first fin structure and the secondfin structure is V-shaped, and wherein at least one of the first grooveand the second groove is a V-shaped groove.
 10. The apparatus of claim8, wherein at least one of the first and second fin structures comprisesat least one coolant inlet port on one of the respective edges, at leastone coolant outlet port on one of the respective edges, and a coolantflow channel therein that connects the at least one coolant inlet portand the at least one coolant outlet port to allow a coolant to flowthrough the respective fin structure.
 11. The apparatus of claim 10,wherein the at least one of the first and second fin structurescomprises: a silicon-based first half-fin structure, the first half-finstructure having a first primary side as the first primary side of therespective fin structure, a second primary side opposite the firstprimary side, a top edge as half of the top edge of the respective finstructure, a bottom edge as half of the bottom edge of the respectivefin structure, a front edge as half of the front edge of the respectivefin structure, and a back edge as half of the back edge of therespective fin structure, the second primary side of the first half-finstructure having a recess, the first primary side of the first half-finstructure having an opening connecting the first primary side of thefirst half-fin structure and the recess on the second primary side ofthe first half-fin structure such that the coolant flowing in thecoolant flow channel of the respective fin structure is in directcontact with the layer of diamond; and a silicon-based second half-finstructure, the second half-fin structure having a first primary side asthe second primary side of the respective fin structure, a secondprimary side opposite the first primary side, a top edge as half of thetop edge of the respective fin structure, a bottom edge as half of thebottom edge of the respective fin structure, a front edge as half of thefront edge of the respective fin structure, and a back edge as half ofthe back edge of the respective fin structure, the second primary sideof the second half-fin structure having a recess, the first primary sideof the second half-fin structure having an opening connecting the firstprimary side of the second half-fin structure and the recess on thesecond primary side of the second half-fin structure such that thecoolant flowing in the coolant flow channel of the respective finstructure is in direct contact with the layer of diamond.
 12. Theapparatus of claim 11, wherein at least the first primary side of thesilicon-based first half-fin structure has a surface roughness of a rootmean squared (RMS) value of 2 microns or less.
 13. The apparatus ofclaim 10, wherein the at least one of the first and second finstructures comprises: a silicon-based first half-fin structure, thefirst half-fin structure having a first primary side as the firstprimary side of the respective fin structure, a second primary sideopposite the first primary side, a top edge as half of the top edge ofthe respective fin structure, a bottom edge as half of the bottom edgeof the respective fin structure, a front edge as half of the front edgeof the respective fin structure, and a back edge as half of the backedge of the respective fin structure, the second primary side of thefirst half-fin structure having a recess; and a silicon-based secondhalf-fin structure, the second half-fin structure having a first primaryside as the first primary side of the respective fin structure, a secondprimary side opposite the first primary side, a top edge as half of thetop edge of the respective fin structure, a bottom edge as half of thebottom edge of the respective fin structure, a front edge as half of thefront edge of the respective fin structure, and a back edge as half ofthe back edge of the respective fin structure, the second primary sideof the second half-fin structure having a recess such that the coolantflow channel of the respective fin structure is formed when the firsthalf-fin structure and the second half-fin structure are mated togetherwith the second primary side of the first half-fin structure facing thesecond primary side of the second half-fin structure.
 14. The apparatusof claim 13, wherein at least the first primary side of thesilicon-based first half-fin structure has a surface roughness of a rootmean squared (RMS) value of 2 microns or less.
 15. The apparatus ofclaim 8, wherein the layer of diamond on at least one of the first finstructure and the second fin structure has a thickness in a rangebetween 10 μm and 500 μm.
 16. A method comprising: polishing a firstprimary side of a silicon wafer; forming a layer of diamond on the firstprimary side of the silicon wafer; micromachining a second primary sideof the silicon wafer that is opposite the first primary side to form atleast one recess on the second primary side; cutting the silicon waferto provide a first half-structure such that a first primary side of thefirst half-structures is covered by a respective layer of diamond and asecond primary side of the first half-structure that is opposite thefirst primary side of the half-structure has a respective one of the atleast one recess; and bonding a silicon-based second half-structure withthe first half-fin structure to form a silicon-based manifold, thesecond half-structure having at least one coolant inlet port and atleast one coolant outlet port.
 17. The method of claim 16, whereinpolishing the first primary side of the silicon wafer comprisespolishing the first primary side of the silicon wafer such that thefirst primary side of the silicon wafer has a surface roughness of aroot mean squared (RMS) value of 2 microns or less.
 18. The method ofclaim 16, wherein forming the layer of diamond on the first primary sideof the silicon wafer comprises forming, on the first primary side of thesilicon wafer, a layer of diamond having a thickness in a range between10 μm and 500 μm.
 19. The method of claim 16, wherein: micromachiningthe second primary side of the silicon wafer to form at least one recesson the second primary side comprises micromachining the second primaryside of the silicon wafer to form at least one recess on the secondprimary side such that at least a portion of the layer of diamond isexposed on the second primary side of the wafer; and cutting the siliconwafer to provide the first half-structure such that a first primary sideof the first half-structures is covered by a respective layer of diamondand a second primary side of the first half-structure has a respectiveone of the at least one recess comprises cutting the silicon wafer toprovide the first half-structure such that the first primary side of thefirst half-structures is covered by the respective layer of diamond andthe second primary side of the first half-structure has a respective oneof the at least one recess that exposes the respective layer of diamondon the second primary side of the first half-structure.
 20. The methodof claim 16, further comprising: attaching a heat-generating device tothe manifold such that the heat-generating device is in direct contactwith the layer of diamond on the first primary side of the firsthalf-structure; and causing a coolant to flow into the manifold throughthe coolant inlet port and out of the manifold through the coolantoutlet port to remove a portion of heat from the heat-generating device.